Pentarch Paladin

Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
As Pentarch Paladin enters, choose a color.
{W}{W}, {T}: Destroy target permanent of the chosen color.

Nykthos, Shrine to Nyx

{T}: Add {C}.
{2}, {T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

Painter's Servant

As Painter's Servant enters, choose a color.
All cards that aren't on the battlefield, spells, and permanents are the chosen color in addition to their other colors.

Iona, Shield of Emeria

Flying
As Iona, Shield of Emeria enters, choose a color.
Your opponents can't cast spells of the chosen color.

Voice of All

Flying
As Voice of All enters, choose a color.
Voice of All has protection from the chosen color.